Mechanoluminescence of SrAl2 O4 :Eu,Dy nanophosphors induced by low impact velocity.

Abstract

The present paper reports the impulsive excitation of mechanoluminescence (ML) in Sr0.97 Al2 O4 :Eu0.01 ,Dy0.02 nanophosphors prepared using a combustion technique. The phosphors are characterized using X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL). The XRD results show that the samples exhibit a monoclinic α-phase in the crystal structure. The space group of SrAl2 O4 :Eu,Dy nanophosphors is monoclinic P21 . The PL and ML spectra of SrAl2 O4 :Eu,Dy nanophosphors are excited using light with a wavelength of 365nm and emission is found at 516nm. The prepared nanophosphors exhibits an intense ML that can be seen in daylight with the naked eye. When a sample powder is deformed impulsively by the impact of a moving piston, the ML intensity initially increases linearly with time, attains a peak value, Im , at time tm , and then decreases with time. The peak ML intensity, Im , and total ML intensity, IT , increase linearly with applied pressure and impact velocity. The ML intensity decreases with successive impacts of load onto the phosphors, and the diminished ML intensity can be approximately recovered by UV irradiation. The activation energy using thermoluminescence is found to be 0.57eV for SrAl2 O4 :Eu,Dy nanophosphors. Copyright © 2016 John Wiley & Sons, Ltd.